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By R. R. Sayers

TWO serious hazards from coal dust confront the bituminous-coal miner- -a physical or safety hazard and a physiological or health hazard. The first threatens the miner with loss of life from coal-dint explosions, and the second with loss of health and earning capacity from inhaling large quantities of the dust. Studies by the Bureau of Mines have shown that coal dust, except some grades of anthracite dust, is capable of initiating an explosion when no explosive gas is present and that its property of extending or propagating an explosion has been responsible for nearly all the widespread explosions that have occurred in bituminous mines in the United States in the present century. For years many mining people believed that low-volatile coal dust was not explosive but not only is it explosive but if the source of ignition is intense, it is as explosive as the dust of many high-volatile coals because the war is creating increased pressure for greater coal production and because of the trend toward greater mechanization in mines, explosion and health hazards from coal dust are likely !n increase considerably.

Jan 1, 1943

By P. Chris Pistorius, Johannes Sono, Rossouw Sono, J. J. Kobus

Different coal properties are important in SL/RN (coal-based rotary kiln) direct reduction of iron ore, and in electrical smelting of prereduced iron ore. These differences were highlighted when a plant which processes titaniferous magnetite had to change to different coal types after decades of operation. Laboratory simulation was used to evaluate two candidate coals, which were similar in volatile content and rank, but differed in reactive maceral content. Direct reduction was evaluated by isothermal experiments using a packed bed of ore and coal, measuring the off-gas composition to determine reaction rates and departure from equilibrium. These indicated reduction to be under mixed control, and quite sensitive to temperature (confirming that the coal reactivity is of importance). An aspect of electrical smelting was assessed by determining dissolution rates of the coal in molten iron at 1550°C. Dissolution rates did correlate with differences in coal structure, as determined by X-ray diffraction, with the more ordered ("more crystalline") coal dissolving faster. The conclusion is that the coal which is more reactive during direct reduction is less reactive during dissolution. However, it is concluded that controlling the temperature during direct reduction offers a feasible method to reconcile the two process steps.

Jan 1, 2003

By Kobus (J. J. ) Rossouw, P. Chris Pistorius, Johannes Sono

"Different coal properties are important in SL/RN (coal-based rotary kiln) direct reduction of iron ore, and in electrical smelting of prereduced iron ore. Laboratory simulation was used to evaluate two candidate coals, which were similar in volatile content and rank, but differed in reactive maceral content. The tests served to evaluate both the reduction rate (during direct reduction) and the dissolution rate of carbon from the coal into an iron bath.Reduction rates of mixtures of magnetite and devolatilised coal were assessed isothermally, using samples of 55 grams. The off-gas analysis was used to follow the extent of reduction. Results are shown in Figure 1 a). Coal B was expected to be more reactive, based on its higher content of reactive macerals (77%, compared with 61% for Coal A). In line with this, Figure 1 a) does show a higher reduction rate with this coal. However, increasing the reduction temperature increases the reduction rate substantially,especially for the less-reactive Coal A.For the dissolution experiments, samples (mass: 250 g) were melted in an alumina crucible (under a nitrogen atmosphere), to give a starting composition around 1%C. When the desired temperature was reached, 25 g of char was added on top of the melt, through a feeding port. Results are shown in Figure 1 b). The more-reactive Coal B was less crystalline (the graphite crystallite size estimated from X-ray diffraction was 4.6Å, compared with 11.4Å for Coal A). This is associated with a lower dissolution rate in iron."

Jan 1, 2003

China's coal energy development, characteristics and relationships with atmospheric pollution are reported. Atmospheric pollution sources from coal combustion are analyzed. Some of the projects for clean coal combustion in the Shanghai area include use of industrial briquettes, investigation of coal combustion additives, and blending combustion of coal with industrial wastes. Coal is China's main energy source, and 80 percent of China's annual coal production is used in combustion devices. Coal-flue gases from the domestic stoves and industrial furnaces are the main atmospheric pollution source. China's atmospheric pollution is, in fact, the pollution of coal-flue gases. To 2000, in view of China's energy needs as a developing nation, the atmospheric pollution from coal combustion must receive our utmost attention.

Jan 1, 1994

By Quansheng Li

Large-scale coal mining will cause environmental problems such as aquifer damage, land excavation and occupation, soil erosion, vegetation damage, and regional landscape damage. The existing coal mine environmental restoration technology is relatively simple, and there is a lack of systematic research on environmental total factors. Based on the mechanism of coal mining damage and the laws of environmental natural succession, the concept of “coal environmental protection mining” is proposed, which combines damage reduction mining and environmental element system restoration. In accordance with the environmental protection principle of “source protection, process damage reduction, and systematic restoration,” a technical system of “coal environmental protection mining” is constructed for the two types of mining damage scenarios: underground mining and open-pit mining. In view of the damage characteristics of underground mining, source environmental protection technology based on optimization of mining process parameters, stability maintenance and damage reduction technology for overlying rock bearing arch shell structure, zoning and time-sharing treatment of surface cracks, and direct drainage irrigation technology for mine water have developed. In accordance with the damage characteristics caused by open-pit mining, land-saving and source reduction damage technology, near-natural stratigraphic reconstruction, topsoil improvement, and environmental storage and utilization technologies for seasonal precipitation have developed. By applying the technology in this paper, the maximum surface settlement value of 12401 working face in Shangwan coal mine was relatively reduced by 25%, the surface cracks have been adjusted from step-type cracks to dynamic small cracks, and since the technical implementation of the Shendong mining area in 2010, the vegetation coverage has increased loss and crushing decreased by 0.06 km2 every year, the environmental restoration period of the dump site was advanced by more than one year, and the vegetation coverage rate increased by 41.78% compared with the background value in the semi-arid area of the victory open-pit coal mine demonstration area. A surface reservoir with a water storage capacity of 400,000 cubic meters has been built, and the seasonal and graded utilization of mine water has been realized. An underground reservoir with a water storage capacity of 1.22 million square meters has been built in the Baorixiler open-pit coal mine.

Jun 25, 2024

By Thomas Downing

WHEN examining a coal property it is customary for the engineer to take channel samples at several coal faces. In doing so the extraneous matter, or partings, which can be removed by hand, or mechanically, with the facilities at hand, or proposed, is rejected. Where there is doubt concerning a stratum it is usually rejected from the main sample but part is taken for separate analysis. The samples are forwarded to a chemist for proximate analyses and determination of British thermal units, and, sometimes, ash fusion. Consideration is given all available commercial analyses but frequently the owner presents only the favorable ones. From the results thus obtained a general evaluation is made, monies are loaned or expended, markets are determined, and realization is estimated. In many instances, such grades are not substantiated and it is time we looked deeper for a basis which will prove more practical. Institute committees are working hard on analytic and use classifications and much valuable information has already been assembled and distributed. However, no single grade can be applied to any particular bed or region. Much study has been given the Pittsburgh No. 8 seam, yet that bed is subject to material differences in a single section; i. e., some strata of a face may differ from others in structure and analysis, particularly in sulfur content. From some localities it yields a good carbonization fuel, while in others it is chemically unfit for such use. Traveling south to the Logan, W. Va., field we find the Cedar Grove (Island Creek) seam a hard, gray splint coal. In the same field, and not far distant, the same bed changes, both structurally and chemically, and consists of excellent gas coal. In Illinois the moisture content of a bed may vary greatly in different localities. We have seen mines in which part of the coal is excellent for special purpose use but is spoiled by the product from another part of the same mine.

Jan 1, 1931

By Thomas F. Downing

When examining a coal property it is customary for the engineer to take channel samples at several coal faces. In doing so the extraneous matter, or partings, which can be removed by hand, or mechanically, with the facilities at hand, or proposed, is rejected. Where there is doubt concerning a stratum it is usually rejected from the main sample but part is taken for separate analysis. The samples are forwarded to a chemist for proximate analyses and determination of British thermal units, and, sometimes, ash fusion. Consideration is given all available commercial analyses but frequently the owner presents only the favorable ones. From the results thus obtained a general evaluation is made, monies are loaned or expended, markets are determined, and realization is estimated. In many instances, such grades are not substantiated and it is time we looked deeper for a basis which will prove more practical. Institute committees are working hard on analytic and use classifications and much valuable information has already been assembled and distributed. However, no single grade can be applied to any particular bed or region. Much study has been given the Pittsburgh No. 8 seam, yet that bed is subject to material differences in a single section;i. e., some strata of a face may differ from others in structure and analysis, particularly in sulfur content. From some localities it yields a good carbonization fuel, while in others it is chemically unfit for such use. Traveling south to the Logan, W. Va., field we find the Cedar Grove (Island Creek) seam a hard, gray splint coal., In the same field, and not far distant, the same bed changes, both structurally and chemically, and consists of excellent gas coal. In Illinois the moisture content of a bed may vary greatly in different localities. We have seen mines in which part of the coal is excellent for special purpose use but is spoiled by the product from another part of the same mine. Many other illustrations could be given but these are sufficient to show that application of any grading of coal must be distinctly local. The actual designation of grade can be given only after detail study of the component parts of the seam, or seams, on the property under considera-

Jan 1, 1932

By Dell H. Adams

COAL EXPLORATION Coal exploration may be defined as the acquisition of data necessary to define and acquire a block of coal which can be mined at a profit. Unlike ore minerals, coal resources are widespread and relatively abundant with supply exceeding demand in almost every case. Thus simple discovery of coal is generally not enough. The chemical and physical variability of individual coal seams, the capital intensive nature of coal mine development, and the changing patterns of utilization require that a multiphase, three-dimensional evaluation be made of each potential reserve. Factors which must be investigated include not only the quantity and quality of the coal but also the geologic, hydrologic, and engineering characteristics of the seam and its surrounding strata. Acquisition of property to provide a secure base for exploration and mine development is equal in importance to the geologic and engineering programs. The successful development of a coal reserve requires that control of coal and, in the case of a strip mine, the surface be in the form of contiguous blocks of sufficient size to support mining. PHASES OF EXPLORATION The high capital risks of coal exploration and land acquisition dictate that a multiphase program be utilized to minimize initial risk. In such a program, phased development of the data insures that each increase in capital expenditures will be justified by a corresponding increase in the level of confidence in the ultimate success of the project. Each phase is designed to provide sufficient data and property control to facilitate the decision whether to proceed to the next phase of development or to discontinue the program (Table 1). The first phase of a typical exploration program consists of a pre-

Jan 1, 1981

By Dell H. Adams

Coal exploration may be defined as the acquisition of data necessary to define and acquire a block of coal which can be mined at a profit. Unlike ore minerals, coal resources are widespread and relatively abundant with supply exceeding demand in almost every case. Thus simple discovery of coal is generally not enough. The chemical and physical variability of individual coal seams, the capital intensive nature of coal mine development, and the changing patterns of utilization require that a multiphase, three-dimensional evaluation be made of each potential reserve. Factors which must be investigated include not only the quantity and quality of the coal but also the geologic, hydrologic, and engineering characteristics of the seam and its surrounding strata. Acquisition of property to provide a secure base for exploration and mine development is equal in importance to the geologic and engineering programs. The successful development of a coal reserve requires that control of coal and, in the case of a strip mine, the surface be in the form of contiguous blocks of sufficient size to support mining.

Jan 1, 1981

By Dell H. Adams

COAL EXPLORATION Coal exploration may be defined as the acquisition of data necessary to define and acquire a block of coal which can be mined at a profit. Unlike ore minerals, coal resources are widespread and relatively abundant with supply exceeding demand in almost every case. Thus simple discovery of coal is generally not enough. The chemical and physical variability of individual coal seams, the capital intensive nature of coal mine development, and the changing patterns of utilization require that a multiphase, three-dimensional evaluation be made of each potential reserve. Factors which must be investigated include not only the quantity and quality of the coal but also the geologic, hydrologic, and engineering characteristics of the seam and its surrounding strata. Acquisition of property to provide a secure base for exploration and mine development is equal in importance to the geologic and engineering programs. The successful development of a coal reserve requires that control of coal and, in the case of a strip mine, the surface be in the form of contiguous blocks of sufficient size to support mining. PHASES OF EXPLORATION The high capital risks of coal exploration and land acquisition dictate that a multiphase program be utilized to minimize initial risk. In such a program, phased development of the data insures that each increase in capital expenditures will be justified by a corresponding increase in the level of confidence in the ultimate success of the project. Each phase is designed to provide sufficient data and property control to facilitate the decision whether to proceed to the next phase of development or to discontinue the program (Table 1). The first phase of a typical exploration program consists of a pre-

Jan 1, 1981

By Marcie A. Greenberg

The Fence Lake Project is located in the Salt Lake coal field, an extension of the San Juan Basin. Geologic formations exposed in the Project area range in age from late Cretaceous to Quaternary. Coal is encountered in the Moreno Hill Formation (upper Cretaceous). Salt River Project (SRP) followed the basic textbook approach for the exploration, regional appraisal, detailed reconnaissance, detailed surface appraisal and three dimensional sampling (physical exploration). SRP is exploring this property as a potential fuel source for the Coronado Generating Station. Therefore, for the physical exploration stage, the quality sampling program was designed from a utility company viewpoint to determine possible impacts to the Station. Exploration drilling was completed in spring, 1982; September, 1982, and summer, 1984. Engineering, environmental, and land acquisition studies were added in the Summer, 1984 Program to more closely evaluate the potential Fence Lake Project coal supply option for the Coronado Generating Station. Studies, including drilling, are ongoing-at this time.

Jan 1, 1984

By J. D. Campbell

"Coal is one of Alberta's major fuel resources, but its distribution, especially in the flat plains region, has been somewhat obscured by surficial deposits. After a period of neglect, easily strippable plains coal is presently approaching a position of dominance in electrical power production, a position it is likely to retain for a number of decades in the face of strong competition from hydro and nuclear power. Accordingly, the Research Council of Alberta has undertaken an inventory survey of the province's supplies of this resource.In the southern part of the province and in the north-central forest-fringe area, some strippable coal is found in the Belly River Formation and its equivalents, but major strippable coal reserves in large areas of central Alberta occur within the Edmonton Formation. The survey is planned on a reconnaissance scale, drilling test holes at 2-mile intervals in selected large areas. It appears to show that, in well-settled regions, large reserves of strippable coal are only to be expected where they have long been known; major presently unknown bodies of coal must be sought in unsettled regions or at depths too great for strip mining. However, such bodies might still be economically competitive with hydro and nuclear power in the production of electric power for some time to come."

Jan 1, 1967

By Marcie A. Greenberg, John C. Patton, R. Tim Thompson

The Fence Lake Project is located in the Salt Lake coal field, an extension of the San Juan Basin. Geologic formations exposed in the Project area range in age from late Cretaceous to Quaternary. Coal is encountered in the Moreno Hill Formation (upper Cretaceous). Salt River Project (SRP) followed the basic textbook approach for the exploration, regional appraisal, detailed reconnaissance, detailed surface detailed and three dimensional sampling (physical exploration). SRP is exploring this property as a potential fuel source for the Coronado Generating Station. Therefore, for the physical exploration stage, the quality sampling program was designed from a utility company viewpoint to determine possible impacts to the Station. Exploration drilling was completed in spring, 1982; September, 1982, and summer, 1984. Engineering, environmental, and land acquisition studies - in the Summer, 1984 Program to more closely evaluate the potential Fence Lake Project coal supply option for the Coronado Generating Station. Studies, including drilling, are ongoing at this time.

Jan 1, 1985

By Robert M. Weidenhammer

For years before the war, Coal had the reputation of being a sick industry. Currently it is operating at peak production and succeeding pretty well in keeping out of the red. But, says Mr. Weidenhammer, it will have a relapse as soon as the war ends unless (1) working capital can be built up; (2) it gets the support of the people and Congress; and (3) a truly long-range national fuel policy is formulated.

Jan 1, 1943

By D. A. Grieve

"Mineable coal seams in the East Kootenay region belong to the Mist Mountain Formation of the Jurassic -Cretaceous Kootenay Group. Three structurally separate coal fields (Crowsnest, Elk Valley and Flathead) are recognized, all of which are characterized by compressional tectonic features such as f aiding and thrust faulting, and by /ate-stage normal faulting. Tectonic history has greatly influenced coal mineability and quality. Coals range in rank from low to highvolatile bituminous, and reactive maceral content ranges from less than 60% to greater than 90%. A wide range of metallurgical and thermal coal qualities is found. Measured reserves (up to 1981) include 1.03 billion metric tonnes metallurgical and 165 million metric tonnes thermal coal. Introduction a) Location -Coal fields of the East Kootenays region occur in the Front Ranges of the Rocky Mountains, within 30 km of the Alberta -British Columbia boundary (Fig. 1). They extend over 175 km north from near the U.S. border, and occupy the regions of the Crowsnest Pass and Elk and Flathead River drainages. The deposits are accessible from Highway 3 (Fig. 1) and various secondary roads. The towns of Fernie, Sparwood, Elkford, Coleman and Blairmore serve the coal industry. East Kootenay coal deposits are contained in three structurally separate coal fields, the Crowsnest, Elk Valley, and Flathead coal fields (Fig. 1). Coal is currently being produced by B.C. Coal (now Westar Mining Ltd.) at Sparwood, by Fording Coal 20 km north of Elkford, by Crows Nest Resources at Line Creek 15 km southeast of Elkford, and by Byron Creek Collieries at Corbin. Westar Mining has also constructed a new mine on the Greenhills Range 8 km northeast of Elkford. Pre-requisite engineering and environmental studies have been carried out on the Elco Mining property, 35 km north of Elkford, and on the Sage Creek coal property near the U.S. border (Fig. 1). b) Coal land tenure -Coal rights in the East Kootenays are either held as freehold land, or are licensed from the provincial government. The former category includes lands acquired under the Railroad Act of 1890. Shortly after this the federal government also obtained 50,000 acres of coal-bearing lands from the Crown Provincial, the so-called Dominion Government Coal Blocks. Major holders of coal rights in the area are Westar Mining and Crows Nest Resources. Large blocks are also held by Fording Coal and related companies, Sage Creek Coal, and Canada Permanent Trust Company as trustee for Elco Mining, and small blocks are held by Byron Creek Collieries and Coleman Collieries. In addition the provincial government holds an area in reserve for possible future use of B.C. Hydro at the extreme north end of the Elk Valley coal field."

Jan 1, 1985

By D. G. Osborne

Transportation cost is a key factor in both the profitability and competitiveness of coal marketing. With coal exportation growing rapidly, moisture control is important. Although in some cases, too much moisture reduction can lead to losses in transportation and pollution problems, there is normally justification for reducing moisture by mechanical means as much as possible. This paper reviews current technology of dewatering coal fines and examines the comparative capabilities of screens, filters, and centrifuges. Financial considerations are stated and implications of capital and operating costs on selection are discussed.

Jan 1, 1985

By Dave G. Osborne

With the growing exportation of coal from North America to the Pacific Rim countries and Europe, has come an increasing awareness of the need to determine economically optimized amounts of incombustibles (ash and moisture contents) for the shipped product. Despite the fact that demand bas caused a steady improvement in selling price, particularly for thermal coals, growing production and transportation costs have compelled producers to keep a sharp eye open for ways and means of minimizing the latter since this probably represents the greatest single potential for making savings. Consequently the Coal Industry has become acutely aware of the economic ramifications of eliminating moisture in particular, thereby producing further saving in the cost of transportation of product from the mine to the consumer. There is, however, a lower limit to which dewatering or drying can be taken and this relates to dustiness which is a function of the characteristics of the coal and the methods used for handling and storage during trans-shipment. Overdrying can lead to serious dust losses and difficulties in handling particularly if the coal contains a large proportion of fines. The ways and means for achieving this "happy medium" of optimization in moisture removal are seemingly undergoing gradual modification largely assisted by the following factors. a) Improvement in effectiveness of coal dewatering and drying equipment. b) Improvement in operational availability and utilization of the equipment. c) The development of surfactants, polymer flocculants and other agents which in many cases can be almost tailor made to suit specific applications.

Jan 1, 1982

By J. L. Thompson

The combustion of pulverized coal is a century-old practice. Many people have investigated coal dust and the residual fly ash particles that re-main after combustion. But the combustion process and fly ash formation mechanism are not under-stood. Working at our Maysville, Kentucky lime plant, the Dravo Lime Company Research team has collected samples of partially burned coal dust from the flame of a pulverized coal burner. Specimens were placed in a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS). Microscopic examination of the particles, together with a large collection of micrographs of lime dust fused to fly ash particles, now make it possible to theorize as to how combustion advances through a piece of coal dust. Coal is a physical mixture of carbon-based compounds interspersed with bits of ash-forming materials, primarily alumina-silicate compounds. The alumina-silicate materials are commonly in angular nodules measuring 100 A to 700 A across their major dimension. It would appear that if the coal particle is in a well mixed gas stream, combustion starts at the surface and advances radially toward the particle center. With poor gas mixing, it is common that combustion moves from one end of a particle and advances on a broad front almost normal to some axis. In either case the combustion process and ash-forming mechanism are the same. As combustion occurs the carbon-based compounds oxidize in a highly exothermic reaction. Heat from the re-action melts the alumina-silicate nodules causing them to flow together and coalesce into an open sponge-like structure. As melting continues surface tension of the liquid and free surface energy causes the sponge-like structure to simplify into fewer, larger pores. Most likely the lighter molecular weight hydro-carbons burn before the heavier species. This means that as the melting ash structure is metamorphosing to a single large pore, there continues to be out-gasing throughout the structure due to combustion. Surface tension will form a spherical piece of fly ash if the ash material is liquid for a sufficient period of time. Out-gasing from combustion of the heavier hydro-carbons will provide internal gas pressure to keep the particle spherical until it freezes.

Jan 1, 1978

By Taylor RN

A simple apparatus for delivering pulverized coal as fuel to a SIROSMELT lance is described, and its performance in smelting tests is evaluated. Using the pulverized coal as fuel, the SIROSMELT furnace performed well in both oxidative copper smelting and reductive smelting (zinc fuming). In both cases the evidence suggests that part of the combustion occurred by indirect oxidation of coal particles entrained in the bath. Oxygen potential measurements made during the zinc fuming tests confirmed the general features of the the non-equilibrium mechanism for zinc fuming proposed by Richards and Brimacombe. The zinc level in the slag during continuous fuming was lower than was predicted using an equilibrium model.

Jan 1, 1987

By Thomas A. Wheeler

The reagents commercially used in coal flotation and their roles are reviewed and discussed According to their function the reagents are divided into often overlapping groups: 1. Collectors 2. Frothers 3. Conditioning Reagents Frothers have by far the largest effect on the amount of coal recovered They act not only in their traditionally accepted function of “bubble makers”, but in coal flotation they serve in a seldom acknowledged role of collectors. A lab flotation study on four samples of different coal ranks shows how these react to various frother families and proves that no froher is the optimum reagent for all types of coal. The advent of new technology in flotation equipment in the past decade has resulted in various novel designs of column cells, Jameson and Centrifloat™ cells, air-sped hydrocylones, etc. All should require special frothers or blends of frothers to meet their specific needs.

Jan 1, 1994